Load share control mechanism



Nov. 25, 1969 H. M. MATHERS ET AL 3,479,321

LOAD SHARE CONTROL MECHANISM Filed May 13, 1968 MN W E S H R a MTm AWW M w am a D L o I m y HM im Y 8 B wv l 5 )2 mm 8 5 2? 11 .%.1 5 mm $5 on S w O N? N? g N E E 1 t QN m. n *4 L q m h.. Q m F AT TORNE YS nited States Patent O Int. Cl. F02b 73/00 US. Cl. 6097 Claims ABSTRACT OF THE DISCLOSURE A pneumatic control mechanism for automatically connecting a master throttle to multiple engines according to whether the clutches coupling the engines to a common load are engaged.

BACKGROUND OF THE INVENTION The present invention relates generally to control mechanisms for multiple engine propulsion systems. More specifically, the invention relates to mechanism for controlling the speed of multiple engines when they are individually and collectively coupled to a common load.

In many types of propulsion systems, and particularly in those designed for marine use, a plurality of engines are coupled by appropriate gear and clutch mechanisms to a common load. Periodically, the load conditions are such to require less than all the engines to drive the load. Accordingly, every engine is provided with a governor thereby enabling each engine individually to power the common load. Because of this arrangement, the engines can be cycled, i.e. alternately coupled to the load, for distributing the wear amongst the engines and gears. However, the governors give rise to a problem when more than one of the engines are coupled to the common load. The governors do not function identically over the entire speed range of the engines. If one governor calls for a slightly different speed than another, the slower engine has a tendency to relinquish the load to the faster engine. Obviously, the unequal load sharing defeats many of the benefits provided by the multiple engine system.

It is accordingly an object of the present invention to provide in a multiple engine propulsion system wherein each engine has a governor for controlling engine speed, a control mechanism for enabling the multiple engines to share a common load substantially equally. It is also an object to include in the control mechanism the ability to control the speed of each engine when individually coupled to the load. A further object is to provide means to control the speed of one or more engines coupled to a common load with remotely located master control means. A still further object is to provide automatic control over the speed of individual and multiple engines in response to the connection of the engines to the common load by the clutches.

DESCRIPTION OF THE DRAWING Other objects and features of the invention are apparent from the description of the invention and the accompanying drawing. The drawing is a schematic of a pneumatic control mechanism suitable for marine use according to the present invention. It illustrates the plumbing network and pneumatic components employed to enable a remotely located pilot throttle to control the fuel racks on marine engines supplying power through clutches to a single propeller shaft. The'pneumatic circuit may be comprised of commercial components.

DESCRIPTION OF THE INVENTION In brief, the present invention is a load share control mechanism for use in a propulsion system employing 3,479,821 Patented Nov. 25, 1969 ice multiple engines drivingly coupled by clutches to a common load. The propulsion system is of the type wherein each engine has a governor linked to the throttle on an engine for controlling the speed thereof. The control mechanism enables control over the speed of a single engine or of multiple engines to be obtained automatically in response to whether the clutch associated with an engine is engaged. The control mechanism permits the individual engines to be alternately coupled to the load when the load conditions are such as to require only the power produced by a single engine. It also insures that when multiple engines are coupled to the load that some of the engines do not relinquish their portion of the load to another engine, i.e. that the engines share the load substantially equally.

The load share control mechanism comprises master control means, slave control means and switching means. The master means comprises a pilot throttle for generating a master speed signal representative of the speed range of an engine used in the system. The pilot throttle is remotely located from the engines, such as on the bridge of a marine vessel. The master speed signal, when coupled to a governor on the engine, causes the governor to establish an engine speed corresponding substantially to that represented by the master speed signal. The control mechanism couples the master speed signal to the governor on an engine when that engine is the sole engine driving the load. When more than one engine is coupled to the load, the master speed signal is coupled to just one engine. The engine to which the master speed signal is applied is hereinafter referred to as the leading engine. The load of the other engines coupled to the common load is slaved to the load of the leading engine. These slaved engines are hereinafter referred to as following engines.

The slave control means adjusts the load of a following engine to substantially that of the leading engine. The slave control means is coupled between the throttles "on the leading and following engines. It causes the throttles on the following engines to assume a physical position substantially the same as that of the throttle on the leading engine. The result is that all engines operate at substantially the same load under the control of the single governor on the leading engine. The slave control means is activated externally by the switching means. When any one engine is coupled to the common load, the control mechanism operates that engine using its own governor. When more than one engine is coupled to the load, the leading engine must be included because its governor controls the speed of the other engines. For the multiple engine operation, the master speed signal is coupled to the leading engine governor and prevented from reaching the governors on the following engines. The slave control means is activated by the switching means when leading and following engines are coupled to the common load.

The switching means controls coupling of the master speed signal to the governors and activation of the slave control means. The switching means operates in response to the engagement of the engine clutches. When a single engine, either leading or following, is coupled to the load, the switching means is informed as to which clutch is engaged. For this case, the switching means coupled the master speed signal to the governor on the particular engine driving the load. When a leading and following engine, i.e. multiple engines, are coupled to the load, the switching means couples the master speed signal to the leading engine and prevents its passage to the following engines. The switching means activates the slave control means to slave the following engines load to that of the leading engine.

The load share control mechanism therefore enables each engine to be operated alone under the control of its own governor. Each engine is operated from a remote location by the same pilot throttle which is automatically coupled to the engine driving the load. When multiple engines drive the load, the control mechanism automatically couples the pilot throttle to the leading engine and slaves the following engine to the throttle setting on the leading engine. The single governor operator of multiple engines insures that they share rather than relinquish the load. The automatic switching insures smooth engine operation.

Pilot throttle 1 comprises the master control means. Throttle 1 is a hand-operated variable pressure valve which generates a variable pressure signal comprising the master speed signal. The throttle is coupled to an air supply reservoir. The pilot throttle has a variable pressure range which causes the governors 8 and 9, when coupled thereto, to adjust fuel racks 2 and 3 between the idle and full 4 positions. The pressure range of the master speed signal corresponds to the speed range of the engines. The fuel racks represent the throttles on the engines. The engines and the common load to which they are coupled are not shown in the drawing.

Following engine clutch 5 and leading engine clutch 6 are air-operated boot type clutches operating to a maximum of 125 pounds per square inch (p.s.i.). The engagement of the clutches signals the load share control mechanism to couple the master speed signal to the proper governor. The operation results whether the forward or reverse clutches are engaged.

The governors 8 and 9 are standard hydraulic-pneumatic operated marine engine governors having arms 12 and 13. The arms are mechanically coupled to the fuel racks 2 and 3 to adjust the position of a fuel rack corresponding to an engine speed setting represented by the master speed signal.

The slave control means comprises positioner 10, slip link 11, governor arms 12 and 13, regulator 14 and cam and cam follower 15. When both engines are coupled to the load, the position of the following engine fuel rack 2 is slaved to that of the leading engine fuel rack 3. Regulator 14 is a variable pressure valve operated by cam and cam follower 15. The air supply for the regulator is coupled to it by decision valve 16 which comprises the means for activating the slave control means. The regulator generates a variable pressure signal which comprises a slave load signal. The pressures of the slave load signal vary over a range corresponding to the idle to full positions of the fuel rack 3. The cam is mechanically connected to arm 13 and has a surface cut so that the cam follower causes regulator 14 to generate a slave load signal having a pressure corresponding to the physical position of fuel rack 3. The fuel rack positions represent engine loads.

Positioner 10 comprises a spring loaded piston having rod 17 aligned with slip link 11. When the pressure of the slave load signal indicates an idle setting on the fuel racks, the piston and spring maintain rod 17 out of actuating engagement with slip link 11. This allows arm 12 to remain in a position such that the fuel rack 2 is at the idle position under conntrol of governor 8. As the pressure of the slave load signal increases the piston moves against the positioner spring causing rod 17 to actuatingly engage slip link 11. This motion is imparted to arm 12 and fuel rack 2 to adjust the position of fuel rack 2 to substantially that of the fuel rack 3.

Valve 34 is a flow control valve which allows a free flow of air in the direction of the arrow and restricted flow in the direction against the arrow. The restricted flow passage of the valve comprises an adjustable needle valve. The needle valve prevents an instantaneous pressure change from being applied across the valve in a direction against the arrow. A time period is required for pressure to build up at the output of the needle valve when pressure is applied to its inlet. Valves 33 and 34 allow free flow of exhaust air from positioner 10, valve 33 being a check valve. Valve 34 prevents instantaneous changes in fuel rack 2 positions. When fuel rack 3 is rapidly adjusted to a new position valve 34 requires passage of a time period before the change in the slave load signal is fully communicated to position 10. Therefore, fuel rack 2 is not instantaneously advanced to a new position. This safeguards against advancing fuel rack 2 before a clutch is fully engaged or before the master speed signal is removed from governor 8. Smooth engine operation is another benefit provided by the flow control valves.

The switching means comprises decision valve 16, gating valves 19 and 20 and disabling valve 21. Decisions valve 16 is a 3-position, 4-way spring centered spool valve. Pilot operators 18 on the left and right sides of valve 16 are in fluid communication with the leading and following engine clutches. The decision valve passes air pressure through the paths indicated by the solid lines when equal pressures are at the left and right pilot operators 18. Valve 16 passes air through the paths indicated by the dashed lines when the pressures at the left and right pilot operators differ.

Gating valves 19 and 20 and disabling valve 21 are 2- position 3-way spring return spool valves. The valves pass air through the path indicated by the solid line when the valve spool is in the spring return position. The single pilot operators on the valves are in fluid communication with the clutches. Pressure exerted on the pilot operators 23 causes the valves to pass air through the path indicated by the dashed lines.

Valve 35 is a hand operated valve for venting the control mechanism line pressure to atmosphere. Valve .35 comprises an ON-OFF switch for the control mechanism.

Shuttle valve 26 is in fluid communication with the clutches. A shuttle valve isolates one air line from another while passing air through it from the line having the higher pressure. Valve 26 is coupled at inlet ports to air lines from clutches 5 and 6 and at an output port to an air line coupled to an inlet port on decision valve 16. Shuttle valve 26 comprises an air supply source for valve 16 whenever either or both clutches are engaged.

Valves 30, 31 and 32 are flow control valves having needle valve passages like valve 34 described earlier. Valve 30 is installed to a port on the dashed line path of valve 21 to provide a slow release of exhaust air from governor 8 to atmosphere. This provides for smooth engine operation by preventing fuel rack 2 from instantaneously returning to the idle position. Valve 31 prevents instantaneous removal of pilot pressure from valve 21 and as a result prevents valve 21 from instantaneously coupling the master speed signal to governor 8. Valve 32 serves to control the rate of speed signal increase to governor 8. The pilot operator 23 switches the valve passage-s between the dashed and solid lines at a pressure generally around 35 p.s.i. Valves 30, 31 and 32 together insure a smooth advance and return of fuel rack 2 throttle setting. This in turn insures smooth engine operation.

The switching means also comprises shuttle valves 24 and 25 which comprise means for establishing fluid communication between valves 16, 19 and 20 and the clutches. The leading and following engines each employ two clutches, one for forward driving of the propeller shaft and one for reverse. The shuttle valves 24 and 25 are coupled to lines tapped into the air supply lines for the clutches. If each engine is provided with a single clutch the need for shuttle valves 24 and 25 is eliminated. The valves 24 and 25 isolate air in the forward and reverse air lines from one another and pass air to valves 16, 19 and 20 from the line of higher pressure. The air passed indicates the engagement of a clutch on the leading and following engines.

Lines 37 and 38 are coupled to air supply reservoirs for coupling operating air pressures to the clutches 5 and 6 respectively. Lines 40 and 41 couple shuttle valves 24 and 25 to the air supply lines 37 and 38. Line 42 couples shuttle valve 24 to the pilot operator on gate valve 19, to the right pilot operator 18 on valve 16 and to one of the two input ports on shuttle valve 26. Line 43 couples shuttle valve 25 to the pilot operator on gate valve 20, to the left pilot operator on valve 16 and to the second inlet port on shuttle valve 26.

Line 44 couples the output port of shuttle valve 26 to the input port on valve 16 through vented cock 35. Line45 couples the output ports of valve 16 to the pilot operator on valve 21 and to the input port on regulator 14.

Line 46 is coupled to pilot throttle 1. Line 46 branches into lines 47 and 48. Line 48 is coupled through gate valve 20 to governor 9. Line 47 is coupled through gate valve 19 and disabling valve 2.1 to governor 8.

The operation of the circuit is first described for the case when both clutches 5 and 6 are engaged thereby coupling the following and leading engines to the common load. The forward clutches are assumed engaged for purpose of illustration. Air pressure of substantially 125 p.s.i. passes from supply lines 37 and 38 through shuttle valves 24 and 25 to gate valves 19 and 20 and decision valve 16. The 125 p.s.i. pressure couples the master speed signal from pilot throttle 1 through valves 19 and 20. Valve 20 couples the master speed signal directly to governor 9 on the leading engine. Disabling valve 21 has substantially 125 p.s.i. pressure at its pilot operator and therefore blocks passage of the master speed signal to governor 8. The 125 p.s.i. pressure at the pilot operator on valve 21 is from the decision valve 16. The air pressure passed through decision valve 16 comprises the decision signal. When at substantially 125 p.s.i. the decision signal indicates that both clutches 5 and 6 are engaged. The decision signal prevents the master speed signal from reaching the following engine and activates the slave control means.

The decision signal is comprised of air from the clutches 5 and 6. When the left and right pilot operators on valve 16 each have substantially 125 p.s.i. pressure applied to them, air pressure from shuttle valve 26 passes through valve 16 to the pilot operator on valve 21 and to regulator 14. The same pressures applied to the pilot operates .18 are coupled to shuttle valve 26. The pressure at one side of shuttle valve 26 passes through valve 16 to regulator 14. This air comprises the decision signal and activates the slave control means as mentioned above. Use of the decision signal as an air supply for the slave control means simplifies the pneumatic circuit.

Regulator 14 varies the pressure of the decision signal according to the fuel rack position on the leading engine thereby generating the slave speed signal. Fuel rack 3 position is established by the master speed signal coupled to governor 9. The slave load signal produced by regulator 14 is coupled to positioner 10 through valve 34. Rod 16 on positioner 10 gradually engages slip link 11 which pushes arm 12 to adjust fuel rack 2 generally to the position of fuel rack 3. This causes the leading and following engines to operate at substantially the same load.

When clutch 6 is disengaged with clutch 5 remaining engaged the load share control mechanism automatically couples the master speed signal to the following engine. Gate valve 20 no longer passes the master speed signal to governor 9 because the 125 p.s.i. pressure at the pilot operator is removed. The pilot pressure at valve 19 still permits passage of the master speed signal. Disabling valve 21 passes the master speed signal to governor 8 because the pilot pressure on valve 21 falls below the activation level when only one clutch is engaged. Flow control valve 32 insures slow advancement of fuel rack 2 to a position corresponding to a speed represented by the master speed signal. The valve 31 insures that coupling of line 47 to governor 8 does not occur instantaneously thereby providing further safeguard against a radically fast advancement of fuel rack 2.

The decision signal is now at zero pressure because valve 16 no longer passes air from shuttle valve 26. The left and right pilot operators are at zero and p.s.i. pressures respectively making the dashed lines the path through the valve. Valve 16 therefore blocks passage of air from shuttle valve 26 to the pilot operator on valve 21 and to regulator 14. Valves 33 and 34 allow positioner 10 to quickly withdraw rod 17 from slip link 11 since they allow free flow of exhaust air in the direction of the arrows. The exhaust air from positioner 10 and regulator 14 vents to atmosphere through a dashed line path of valve 16. The following engine is therefore operated under influence of its own governor, the master speed signal is blocked from the leading engine and the slave control means is inactivated.

When the leading engine is again connected to the load along with the following engine the master speed control signal is switched back to governor 9. Gage valve 19 continues to pass the master speed signal but is blocked from governor 8 by disabling valve 21. Valve 20 passes the master speed signal to governor 9. Valve 34 insures a gradual slaving of fuel rack 2 to the position of fuel rack 3. Valve 30 assists because it causes a slow release of pressure from governor 8 to atmosphere. The equal pressures at the left and right pilot operators of valve 16 again give a decision signal of 125 p.s.i. This pressure blocks the master speed signal from governor 8 and actuates regulator 14. The two engines are therefore operated under control of governor 9 with slave control means slaving fuel rack 2 to the positions of fuel rack 3.

If the following engine is now disconnected from the load the decision signal again falls to zero p.s.i. The gate valve 19 blocks passage of the master speed signal to governor 8. This is because the pilot operator pressure at valve 19 is now zero. The zero p.s.i. decision signal pressure deprives regulator 14 of an air supply for generating the slave load signal therefore the slave control means is inactivated. The master speed signal is coupled to governor 9 through valve 20. The leading engine is therefore operated under control of its own governor, the master speed signal is blocked from governor 8 and the slave control means is inactivated.

It is believed that the invention will have been clearly understood from the foregoing detailed description of my now-preferred illustrated embodiment. Changes in the details of construction may be resorted to without departing from the spirit of the invention and it is accordingly my intention that no limitations be implied and that the hereto annexed claims be given the broadest interpretation to which the employed language fairly admm.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a multiple engine propulsion system of the type therein at least leading and following engines each has a governor coupled to a throttle for controlling engine speed and each engine has a clutch for coupling to a common load, a load share control mechanism comprising master control means for generating a master speed signal representative of the speed range of an engine causing the governors when coupled thereto to establish an engine speed corresponding substantially to that represented by said master speed signal, slave control means coupled to the throttles on the leading and following engines for adjusting, when activated, the load of the following engine to substantially the load of the leading engine, and

switching means responsive to clutch engagement coupled to said master and slave control means and to the clutches for coupling said master speed signal to a governor and for activating said slave control means,

said switching means coupling said master speed signal to a leading or following engine when either one is coupled to the load and coupling said master speed signal to a leading engine when both leading and following engines are coupled to the load,

said switching means activating said slave control means when both leading and following engines are coupled to the common load.

2. The mechanism of claim 1 wherein said master control means comprises a remotely located pilot throttle for generating said master speed signal.

3. The mechanism of claim 1 wherein said slave control means includes regulator means coupled to said switching means and to the throttle on a leading engine for generating a slave speed signal representative of the throttle settings thereon,

positioner means coupled to said regulator means and the throttle on a following engine for adjusting the load of the following engine substantially that represented by said load signal.

4. The mechanism of claim 3 wherein said regulator means includes a cam and cam follower operatively coupled to the throttle on a leading engine; and

variable signal means operatively coupled to said cam follower for generating a slave load signal representative of a throttle setting.

5. The mechanism of claim 3 wherein said positioner means includes a slip link operatively coupled to a throttle of a following engine, and positioning means operatively coupled to said slip link and coupled to said regulator means for adjusting the following engine throttle to a position substantially that represented by said slave load signal. 6. The mechanism of claim 1 wherein said switching means includes leading and following gate means coupled to said master control means and the governors and clutches on the leading and following engines for coupling said master speed signal to a governor in response to clutch engagement, disabling means coupled to said following gate means and to a following engine governor responsive to clutch engagement for preventing coupling of said master speed signal to a following engine, and

decision means for generating a decision signal representative of clutch engagement, said means coupled to the clutches and responsive to the engagement thereof and said means coupled to said disabling means and to said slave control means,

said decision signal causing said disabling means to prevent coupling of said master speed signal to a following engine governor when both leading and following engines are coupled to the common load,

said decision signal activating said slave control means when both leading and following engines are coupled to the load.

7. The mechanism of claim 6 wherein said propulsion system clutches and said load share control mechanism are pneumatically operated with said master speed, slave load and decision signals being air pressure signals.

8. The mechanism of claim 7 wherein said gating and disabling means comprises 2-position, 3-way spring return spool valves having a single pilot operator, said gate valve pilot operators coupled to the clutches, said disabling valve 6 pilot operator coupled to said decision means, and wherein said decision means comprises a 3-position, 4-way, spring centered spool valve having two pilot operators coupled to the clutches and having an inlet port coupled to the clutches and having outlet ports passing air from said inlet port when air pressure at said pilot operators indicates clutch engagement, air passed by said outlet port comprising said decision signal.

9. The mechanism of claim 8 wherein said slave control means includes a variable pressure valve having an inlet port coupled to the outlet ports of said decision valve whereby air coupled to said variable pressure valve activates said slave control means.

10. In a marine engine propulsion system of the type wherein at least leading and following engines each has a pneumatic governor coupled to a throttle for controlling engine speed and each engine has a pneumatic clutch coupled by air lines to an air reservoir for coupling to a common propeller shaft, a pneumatic load share control mechanism comprising a pilot throttle for generating a master speed signal including a hand operated variable pressure valve adapted for connection to an air supply reservoir,

leading and following gate valves having pilot operators coupled to the air supply lines to the leading and following engine clutches respectively, said gate valves coupled to said pilot throttle and the governors for coupling said master speed signal to governors on the leading and following engines respectively,

a disabling valve, having a pilot operator, coupled to said following gate valve and a following engine governor for preventing coupling of said master speed signal from said gate valve to the governor,

regulator means including a cam and cam follower operatively coupled to the throttle on a leading engine and to a variable pressure valve, said variable pressure valve for generating a slave load signal representative of the throttle setting when air is supplied to an inlet port of said variable pressure valve.

positioner means for adjusting the throttle on a following engine to substantially the setting of the leading engine throttle including a slip link coupled to the throttle on a following engine and a spring loaded piston operatively coupled to said slip link and to said regulator variable pressure valve causing following engine throttle adjustments in response to said slave load signal, and

a decision valve having inlet and outlet ports and left and right pilot operators, said inlet port coupled by a shuttle valve to the air lines supplyiing 'air to the clutches and said pilot operators coupled to the air lines supplying air to the clutches causing air at said inlet port to pass through said valve when both leading and following clutches are engaged, said outlet port coupled to said disabling valve pilot operator and to said regulator variable pressure valve inlet port.

References Cited UNITED STATES PATENTS 2,307,334 1/ 1943 Peek. 2,339,989 1/ 1944 Glanville et a1. 2,349,333 5/ 1944 Armentrout. 2,501,228 3/ 1950 Light. 2,527,424 10/ 1950 Johansson. 2,666,295 1/ 1954 Stevens 60-97 MARTIN P. SCHWADRON, Primary Examiner R. R. BUNEVICH, Assistant Examiner US. Cl. X.R. -13529 

